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Why aren’t any JP-1-type (extreme-narrow-cut) fuels in use today?
JP-1 was the first U.S. military standard jet fuel (hence the 1 in the designation), with its specifications issued in 1944; it was an extremely narrow-cut, high-alkane kerosene, not far from what would later become RP-1.  As a result, it had both a very low freezing point (-60C maximum) and a very high flash point, a combination that is the Holy Grail of the aviation-fuel industry.  Its only drawback was that it was hard to produce (since, to quote John D. Clark in Ignition!, “not many refineries in the country could produce such a product with their available equipment and crudes”), and therefore expensive and in chronically short supply, which prompted the development of wide-cut fuels (first the extremely-wide-cut JP-3, followed by the somewhat saner JP-4) and the gradual disappearance of JP-1 (although, judging by mentions in various aircraft accident reports, it apparently was still being produced into the 1970s).
On the other hand, those were 1940s/50s refineries that had difficulty producing JP-1 - and what would be tough beans for a 1940s refinery would be no trouble at all for a 21st-century refinery, thanx to the polymerisation/cracking/hydrogenation/witchcraft/etc. techniques originally developed to turn all the heavier, less-profitable petroleum fractions (and the gaseous, hard-to-store ones) into gold, I mean gasoline, which could easily be adapted to turn even the most recalcitrant crudes into extreme-narrow-cut, JP-1-type fuels (especially given that RP-1 is an even tighter kerosene than JP-1, albeit not by much, and yet we haven’t had any trouble getting ahold of that in the vast quantities needed for launching things into space); so why haven’t we returned to JP-1 and similar fuels, which have freezing points rivalling Jet B combined with flash points that blow away (pun intended) even Jet A?

If it has gotten easier to make JP-1, it has also gotten easier to make Jet-A/A1/B; the wider-cut ones will always be cheaper, so if your engine can burn it, why pay more than you have to? If nobody buys the narrow-cut one, why bother making it?

@StephenS: Because it's safer (higher flashpoint) and more versatile (lower freezing point)?

JP-1 is not in use because it's expensive and there's cheaper ways to deal with flash point and freezing point.

The navy developed JP-5 for carrier use where a higher flash point is required, and it is easier and cheaper to produce than jp-1
A higher flash point isn't that big a gain in most use cases, it's not as if the fuel is going to instantly burst into flame if it reaches 40°C - with good equipment and safety practices Jet-A(1) is still pretty safe to handle
Anti-gelling additives, tank heaters and recirculators work very well to keep fuel from gelling or freezing. This has proven very effective, BA-38 is the only case I can think of in recent memory where ice in fuel has caused an issue, and that was due to water ice crystals rather than the fuel itself, which didn't freeze. JP-1 wouldn't have helped in that case

@Sean concerns are justified, as a few "rockin' in the Bakken rail cars carrying low flash crude went up in flames.  Fuel properties can be adjusted with weather, and additives are very helpful, as is inerting the air in the tanks. The science has advanced with some hard earned lessons.

curious, did you all have issues with carbon deposits with JP-5?  I understand they allowed some ringed compounds that may not have been in JP-1 to reduce costs.

Not to promote Darwinism here, but unlike subsidized and inefficient (who cares if we run a deficit, it's only money) operations, businesses need to earn their keep.  And writers should (I have learned this lesson) do some research (just click and open up another tab) before spewing such nonsense.

Although rocket launches draw all the glamor and press, far less RP-1 is needed than the huge amount of Jet A consumed every day.
ANY step added to an industrial process costs money.  Airline tickets do not generate as much revenue as satellites.

The oil industry, though much maligned in the past, has done a tremendous job keeping energy costs stable in recent years, and, adjusted for 1965 dollars, fuel is almost as cheap as water.
It is all demand driven.  Concerns about lower quality as valid, and should be addressed, particularly as an aspiring new professional.  But, doing homework as is time honored as the way things were in "the good old days".  It may be, with improvements in jet engine design,
such tight tolerances are no longer needed.


text:
Did Boeing or Lockheed ever seriously consider releasing a widebody airliner powered by low-bypass engines?
During the 1960s race to build the first widebody jetliner, each of the three major engine manufacturers was racing to put out a high-bypass engine for one of those jumbo jets:

Boeing went with Pratt & Whitney’s JT9D for their 747.
Douglas (which soon became McDonnell Douglas) chose General Electric’s CF6 to power the DC-10 (Airbus also chose the CF6 for the A300 when they jumped in a couple of years later).
Lockheed, for the L-1011, put their money on Rolls-Royce’s RB211.

Of the first three widebodies, only the DC-10 (whose power plant was a fairly straightforward conversion of the TF39 used on the C-5A Galaxy, which had been the first high-bypass turbofan ever to enter production) escaped being held up by engine difficulties; the L-1011 was held back for years when the RB211 ran into serious delays which allowed the DC-10 to beat it to market and strangle the TriStar in the schoolyard, 1 nearly bankrupting Lockheed in the process.
What isn’t as well known is that Boeing experienced delays of similar severity with the JT9Ds that were to power the 747; for a long while, there were rows upon rows of 747s sitting on the ramp at Boeing Field, complete but for having concrete blocks hanging from their pylons in place of the engines that could not yet be trusted on a production airliner.  Only Boeing’s massive head start enabled the 747 to beat the DC-10.2
Did Boeing or Lockheed ever seriously consider releasing an interim widebody with low-bypass turbofans (for instance, a 747 with eight JT8Ds mounted two to a pylon in conjoined pods, B-52-style) while they waited (and waited) for the high-bypass engines to become ready?

1: It wouldn’t be accurate to say that it strangled the TriStar in the cradle, given that the L-1011 did, in fact, manage to enter production and sell 250 aircraft.
2: Enabling Boeing to remain solvent in the process, as Boeing, like Lockheed, had bet the farm on their jumbo jet.  Unlike Lockheed, they didn’t lose it; however, if the 747 had been a failure, it would have bankrupted Boeing.

Most OEMs - certainly not only Boeing and Lockheed in the 747 and TriStar-cases - "bet the farm" when introducing a new type. Break-even often takes 10 (Sadraey, 2013) to 20 years, and only a few aircraft turn into true money makers (A320/A330/737/747/777, with A350 and 787 on their way to become one).

I think of it like this:
It was possible to create the 747 because the revolutionary JT9D was created for it.
Likewise, it would not have been possible to create the 777 if the largest engines ever produced had not been designed for it.
It seems to me that the revolutionary airliners are able to come about as a result of cutting-edge powerplant technology that is coming to market just in time to be utilized by the new airframe.
(I do realize that Boeing decided to make the 747 and needed/requested/hired Pratt & Whitney to produce the needed powerplant.  It's not like the JT9D was invented so Boeing said, "Hey let's make an airplane to use this engine".  It was a coordinated effort by both parties).
So what good is a 747 without the high-bypass engines it was designed for?  Nothing.
Making any effort to put loud old-tech engines that burn lots of fuel on a revolutionary aircraft that is tested and optimized for the current cutting-edge engines benefits no one and costs a lot.
Not to mention that the different weight engines would most likely upset the aircraft's very carefully designed center of gravity and make it unflyable... Not to mention government regulatory certification requirements for the changed aircraft which has not been designed for or wind tunnel tested for the different engines...

I am not aware of any manufacturer making a serious proposal to develop a jumbo jet with low bypass-ratio engines. Most airline manufacturers tend to develop a plane from  customers requirements, whether that customer is military or civilian. Civilian airlines in the late 1950s were already nervous about the much higher costs for jet-powered aircraft and there was no call at this time for an even larger plane.
To get the most value for their development efforts, airplane companies tend to look at if they can develop a commercial and military version. As an example, Boeing tries to develop a commercial variant to all of their military planes and vice versa. Starting with the Boeing 307 Stratoliner and continuing with the the Boeing B-52 Stratofortress and the Boeing B-47 Stratojet, Boeing worked to develop a passenger variant as well. There was discussions with making the B-52 into a passenger plane, but commercial airlines were not interested. Some of the reasons were the the hull was very narrow, much of it un-pressurized and in many ways, it  would have been ill-suited for passenger use. The plane would have had identical engines to the B-52. I could not locate any drawings of what it would look like. The push for a passenger plane became the Boeing 367-80, which developed into the Boeing KC-135 Stratotanker and the Boeing 707, which entered into service in 1958.
Lockheed had it's hands full with fulfilling orders for the Constellation. It developed some great military planes, but never pursued a passenger jet until the Lockheed L-1011 TriStar which first flew in 1970.
After World War II, Douglas lost a lot of military business and was forced to scale back. It's first jet that became a passenger jet came out of the development of a tanker for the Air Force that eventually became the Boeing KC-135 tanker. The reason they developed the Douglas DC-8 was that Pan Am ordered 20 of them and they could see the future was jet-powered.
The next big jump in airplane size came out of a development effort by the Air Force. In 1964 they asked Boeing, Douglas, General Dynamics, Lockheed, and Martin Marietta to develop a prototype for the CX-HLS cargo plane. This was much larger than anything that existed at the time. In this proposal, the Air Force was asking for high efficiency engines as well as the ability to carry a lot of weight. The two final prototypes became the Lockheed C-5 Galaxy and the Boeing 747.
By this time, the age of low-bypass-ratio engines was over because of the much better efficiency available in newer high-bypass engines.

This is a good answer. In addition for your last point, keep in mind that podded engines may be beneficial occasionally (depending on the overall design) but it's hell for reliability. If one engine malfunctions or fails completely, the probability and potential for a cascading failure is far greater, an engineering sacrifice unacceptable for commercial airliners.

Minor nitpick: You might argue that the Jetstar was the first Lockheed passenger jet, although its passengers were not the typical fare-paying variant.

I can think of two disadvantages that made these (or other) OEMs decide not to release a widebody airliner powered by low bypass-engines, certaintly in case such an aircraft would be a derivative of a high(er) bypass design.

Fuel efficiency. Lower bypass-ratio engines are less fuel efficient than higher bypass-ratio engines. Lower fuel efficiency means decreased range for a given payload. Both are bad, and might even break the business case (particular routes requiring a large range, poorer economics if fixed cost has to be paid by a smaller number of passengers) for acquiring this aircraft.
Additional engineering. Doubling the number of engines also requires a doubling of support systems (lubrication, fuel lines, engine controls, diagnostics, and so on). That seems much too much trouble for a relatively small gain.

The OP asked whether actual manufacturers considered a low-bypass powered airliner, not about (dis)advantages of such a design.

Those disadvantages are reasons why manufacturers wouldn't seriously consider low-bypass powered airliners.

@Hobbes: Even as just an interim solution for until they could get the planes working with high-bypass engines?

'just an interim solution' would require a lot of engineering hours, right when Boeing was in the middle of designing the 747. The interim solution would have delayed the 747 project.

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Why is the CFM56 produced with two different thrust reverse options?
According to Wikipedia, the CFM56 could support several reverse thrust options, and it appears that it has actually been built with 2:

Boeing seems to prefer the cascade type
Airbus seems to prefer the pivoting door type

Is this a simple case of catering to customer preferences, or is there a more in-depth reason for having multiple reverse thrust options?

On a turbofan the reverser is usually part of the nacelle, not of the engine.

… and the nacelle has to be designed for every aircraft+engine combination anyway, so choosing different reversers in different cases does not really add much extra work.

Most likely to allow for increase installation flexibility depending on the choice of engine cowlings to be used on a given aircraft design.

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What does "500 and 1" mean?
In this AVWeb article, numerous references are made to 500 and 1, with other references to 3,000 and 5.
Based on the statement The current observation was 800 overcast and four miles visibility (in the second paragraph), I would presume that 500 and 1 means a 500 foot ceiling and one mile visibility, is that correct?

I think you have a typo in your question -- you say "...was 800 overcast and four miles...", but then say "...a 500 foot ceiling and one mile..."

@Johnny, no typo: based on the second statement, I was assuming a meaning for the first statement. The question was for confirmation that my assumption was correct. I have edited to add some clarity.

Yes, 500 and 1 is 500 ft ceiling and 1 mile visibility.

Thank you. It was your link to that article that prompted the question in the first place.

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What is a "Pod-Pak"?
The following image, from the Qantas Heritage Collection (via aussieairliners.org), shows the flight crew inspecting the 'Pod-Pak' prior to departure:

Based on the angle of their heads, I'd assume it's the engine-looking device to the right of frame.
Also, what are the rocket engine-like tubes at the left of frame?

A Pod-Pak is a aerodynamically shaped enclosure to transport an extra engine under the wing.
From 'Flying Magazine', Nov 1959:

Spare engine in “Pod Pak” is the airlines' modern method of
  transporting extra engines to maintenance points. Nine major airlines
  flying Boeing 707s have ordered Pod-Paks. This spare suspended below
  the wing of a Qantas Airline's 707 shows the Pod Pak suspended from
  the airplane's front wing spar by means of two fittings and to the
  landing geard support rib by four bolts. Fairings streamline ends of
  the engine and normal engine cowls enclose the sides. No structural
  changes are required in the airplane's wing and, when not needed,
  Pod-Pak can be removed completely.

The exhaust pipes of the Pratt & Whitney JT3C turbojet engine on the left of the picture are an attempt to reduce the noise of the engine. They should aid in the mixing of the core exhaust stream and the freestream air which is quite a noisy process.
The successor to the JT3C, the JT3D, was a turbofan. In a turbofan there is a layer of bypass air between the core exhaust stream and the freestream which reduces the noise and increases the efficiency. Later B707s fitted with the JT3D engines did have not have the 20 pipes exhaust. Most of the aircraft which were originally fitted with the JT3C where later retrofitted with the JT3D.


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What is the difference between instrument privileges and instrument rating?
According to FAR 61.153(d), a pilot may use a foreign commercial or ATP certificate as a prerequisite for getting a US ATP.
To do so, an applicant must:

Meet at least one of the following requirements:
  ...
  (3) Holds either a foreign airline transport pilot license with instrument privileges, or a foreign commercial pilot license with an instrument rating, that... (emphasis added)

What's the difference between "instrument privileges" and "Instrument rating"?

The short answer is that the privileges are what the rating confers, and there are ways to get those privileges other than having the rating.
A commercial pilot licensee in most jurisdictions that follow ICAO certification guidelines may fly small planes for hire, doing service as a courier, air taxi, crop duster, etc. These do not necessarily require flying in IMC or in Class A airspace, and so a CPL holder must also have a separate "instrument rating certification" in order to fly IFR.
ATPL licensees fly in Class A as a matter of course, and that also often requires ascending and descending through the cloud ceiling which is IMC by definition. Therefore, the requirements for an ATPL in ICAO-compliant jurisdictions inherently include those required for the "instrument rating" applied separately to lower certification levels (private/commercial), and the resulting license for an airline pilot confers the same "instrument privileges" that the rating would.
Thus the difference in terminology; an ATPL holder in another country has "instrument privileges" as a consequence of his basic license and so does not need a specific "instrument rating". The same is not true for CPLs and so the law specifically requires the instrument rating as a prereq for a foreign CPL seeking an FAA ATPL.

That was a great answer last week, but it took the weekend thinking about something else entirely for it to make sense this morning.

This arises from a difference in how instrument privileges are granted by the FAA.  Private and commercial ratings do not include instrument privileges but the ATP rating does.
This means that for a commercial pilot to have instrument privileges the pilot must also have an instrument rating.  To apply for an ATP rating the pilot must have instrument privileges (from an instrument rating) and once the ATP is passed, the pilot no longer has an instrument rating, just an ATP rating.  The ATP rating itself grants instrument privileges.
The wording in the regs you post account for this.  The applicant must have instrument privileges and this can either be from a foreign commercial+instrument rating or just a foreign ATP rating (that grants instrument privileges).

Instrument privileges allow you do instrument things and an instrument rating is something that confers instrument privileges.


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How much responsibility does ATC have to alert a flight about being in a dangerous situation?
There have been quite a number of accident reports referenced here at Aviation.SE about commercial (passenger or freight) flights executing controlled flight into terrain on approach for landing. The accident reports always seem to revolve around the pilots not knowing they are too low, failing to recognize or respond to the GPWS, etc.
While I understand that the pilot in command has the final say on what happens on board the aircraft, ATC is responsible for giving the PIC instructions to get him safely to the end of the runway.
In the case where ATC has given the PIC the approach route, whether VFR (flight following) or IFR, how much time, ability, and requirement does ATC then have to monitor that flight to ensure that it's on the expected course and at expected altitudes? In other words, how much responsibility does ATC have for failure to monitor the situation and allow these accidents to happen?
If necessary, differentiate between different CAAs, but I would think the answer would be fairly similar around the world.
There are a couple of nice answers, but they're not addressing (in my head, at least) the question I was attempting to ask, so it seems I didn't ask it well. I'll clarify further:
In a situation such as Eastern 401, the pilots had already contacted the tower to indicate that they had an issue - the nose gear lock light failed to illuminate. While attempting to determine what the cause of the problem was (bulb burnt out or gear not actually locked), they forgot to aviate and flew into the ground. In a situation like this, particularly where ATC has been notified that there was an issue with the flight, it seems to me that they (ATC) would have been more alert to the flight and notified the pilots that they were descending when they should have been holding a steady altitude.
This is the type of situation that I'm asking about (though not specifically EA401), and I'm wondering what role, if any, ATC should or does take in monitoring and alerting flight crews to altitude deviations, especially on approach.

This is very broad, too broad to be answered as there are so many potential situations and each would have to be discussed to get an answer

On the one hand, @GdD, I can see that and agree with you. On the other, however, ATC deals with hundreds/thousands of flights daily crossing in a multitude of directions & altitudes and they're required to keep minimum separations (in many potential situations). Helping to ensure landing aircraft keep a minimum separation from the ground (instead of another aircraft) doesn't seem that far outside what they do already.

I agree with Freeman.  A sufficient answer could, for example, explain the MAWS system and how it's supposed to be operated.

This is potentially a very broad topic, but here's some information about the US.
As a general principle, safety is ATC's first priority so obviously they have a basic responsibility to provide whatever information and action are required to keep aircraft safe:
FAA ATC orders 2-1-1:

The primary purpose of the ATC system is to prevent a collision
  between aircraft operating in the system and to provide a safe,
  orderly and expeditious flow of traffic, and to provide support for
  National Security and Homeland Defense.

The orders explicitly say that ensuring separation and issuing alerts take priority over everything else. Section 2-1-2, DUTY PRIORITY:

Give first priority to separating aircraft and issuing safety alerts
  as required in this order. Good judgment must be used in prioritizing
  all other provisions of this order based on the requirements of the
  situation at hand.

Section 2-1-6, SAFETY ALERT defines what an alert is and when to issue one (this section is referenced throughout the orders):

Issue a safety alert to an aircraft if you are aware the aircraft is
  in a position/altitude that, in your judgment, places it in unsafe
  proximity to terrain, obstructions, or other aircraft. Once the pilot
  informs you action is being taken to resolve the situation, you may
  discontinue the issuance of further alerts. Do not assume that because
  someone else has responsibility for the aircraft that the unsafe
  situation has been observed and the safety alert issued; inform the
  appropriate controller

It's difficult to say much more than that because there are so many possible scenarios. But you can search for "safety alert" in the orders and the AIM to get more information and there's some limited content in the orders 5-15 about radar displays and alerts.
If ATC fails to issue a safety alert and that leads to an accident, then it will be mentioned in the NTSB report, e.g. LAX04FA205:

Contributing to the accident was the failure of both the Center and
  TRACON controllers to properly respond to the aural and visual Minimum
  Safe Altitude Warning System (MSAW) alert.

But actually acting on a safety alert is entirely the pilot's responsibility, of course (this is from the AIM 4-1-16):

Once the alert is issued, it is solely the pilot’s prerogative to
  determine what course of action, if any, to take

how much time, ability, and requirement does ATC then have to monitor that flight to ensure that it's on the expected course and at expected altitudes?

ATC must not vector you into the ground (besides not vectoring you into other aircraft, which is their primary responsibility). For this they have minimum vectoring altitudes (MVA) indicated on the radar scopes and when issuing vectors, must assign you safe altitude.
Beyond that, any warnings are provided on best-effort basis and their ability to alert aircraft about unsafe position is often limited:

They don't have detailed map of obstacles and their heights, only the minimum vectoring altitudes that usually cover large areas and are rather generous. So aircraft often fly lower under VFR or when executing a visual procedure (e.g. a circling approach) and it is safe as long as they have ground in sight. But when pilots lose suddenly ground visibility, they usually have lot of work trying to get oriented, so they don't report they lost it to the controller, so the controller can't advise them. That is how many CFIT accidents happen.
How busy the controller is varies wildly. But a busy controller might have 20 aircraft on their scope. With that many they spend most of the time looking for conflicts, which the system also helps them with, and coming up with routes to avoid them. That doesn't leave much time and mental capacity to look for aircraft below MVA.

On emergency situations, or even on abnormals, the ATC will provide the instructions, according to the manuals and procedures. All the instructions, given by controllers, can be, at any time, avoided by pilots, if they interfere on the safety, for example, courses (into bad weather), altitudes (if the aircraft can't reach or maintain), turns (if they are unable to comply), and pilots will say that, giving alternatives.
On radar service, the ATC is responsible for the navigation, and all the responsibilities go under them.
So, controllers have all the skills to conduct all the situations, including the emergency ones, and if they are not possible to be accomplished by the crew, they will say that and give another opition.


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How does 220 kN of engine thrust create the 700 kN required to maintain the altitude of an A320?
On the Airbus A320, the two engines produce about 220 kN in cruise, whose weight is about 700 kN (about 70 tons). The lift / drag ratio in cruise is about 15 (likely higher), meaning in cruise lift = 700 kN and drag = 47 kN (or less).

What is the accurate explanation of the figures above? How does 220 kN of thrust create the 700 kN required to maintain altitude and the 47 kN required to maintain speed?

Please note that drag increases with the square of velocity. And that airliners have operational Mach number limits.

I can't produce any equations, but the forward motion is what creates the lift. If you had a completely drag-free glider and no wind it could stay in straight flight forever with all forces in balance. Gravity counters lift. And no drag, so no thrust. The reason it must eventually come down is because the drag force slows it down. Less speed equals less lift. In a powered plane the thrust simply needs to balance against the drag. Then all forces are in balance again, so the only force the engines need to balance is the drag force.

I know this is the usual explanation and maybe you are just right to restate what I've read a thousand of times, but I can't make sense of that easily. The implication for the drag-free glider, is indeed surprising, but very logical.

To be honest, I have trouble with this too. Sometimes I think I've got it, then I start to doubt. Maybe later on I can reword this so it makes more sense

Key is to rememeber that work is force scalar speed. It is all clear then.

To be fair, the drag free glider thought experiment is probably the most counterintuitive thing for me since lift creates drag, besides any further parasite drag from the glider body.


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Is it normal for the flaps to move like this?
I noticed this particular portion of the flaps moving differently from rest of the wings. In the attached picture, the middle flap is raised. Is this considered normal?
The landing and takeoff in this flight was normal, but the flaps moving like this made me a little (lot) uncomfortable! I've added a video, as well.

Video on Youtube

Related

How can this be a duplicate? The other question is answered by explaining why there is a gap in the flaps, and how (and why) this inner "high-speed aileron" (flaperon) is used at high speed when the regular outer aileron is locked. It doesn't at all answer what happens at low speed.

I believe the engine is mounted in front of that part.
This means that if the part moved along with the rest of the spoiler the jetblast would be deflected down which will create an upward force on the wing. You don't want that while you have full spoiler deployment.
Putting a gap in the spoiler will reduce stress on the full spoiler from the jet blast. This leads to less expensive maintenance as the stresses are reduced mostly to a single panel and its attachment points.
As @Ron points out the flap geometry is such that you can't have the full flaps adjacent to each other without them jamming up when they deflect. Putting an extra panel between them lets it move on top of the other 2 flaps when necessary.

It's a Boeing 787-8, if that helps? I found this picture of the plane and it looks like you're right about engine being mounted in front of the part there: https://i.ytimg.com/vi/a2GlO16qiIA/maxresdefault.jpg

The engine isn't there, but look at the wing geometry. That panel can't lower because it would jam the flaps on either side. So they made it a spoiler

As noted by @Pondlife, that's not a flap but an aileron, that's why it's not moving like the flaps. See http://aviation.stackexchange.com/a/8905/1031 for more details.

@Albireo It is a flaperon. Labeling it as merely an aileron is incorrect, as is labeling it "not a flap".

All the comments saying it can't lower didn't bother to watch the video attached to the question - which shows the part lower - even below the other parts at some points. The statement that it will jam is shown clearly to be inaccurate.

It's not so much about jamming as hinging. Since the geometry of the wing has a curve at that point the flap hinges cant extend all the way to the midpoint, you therefor need a small panel in between to break the curve. It would appear that they did not however add both spoiler and flap in the short section though, so when spoiler is deployed the flap flips to the UP position. Not sure why this made you uncomfortable though.


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What is the decision- and workflow during a strategical rerouting?
Consider a commercial longhaul flight receives a warning about severe weather on its intendend route, a few hours of flight time out. What would be a typical work- and decisionflow between pilots, dispatchers and controllers for the rerouting of this flight?
To have a more specific scenario, lets assume the flight is bound to the US westcoast from Europe and the pilots receive the weather forecast when already in Canadian airspace (not oceanic).

Good question! One major problem of long-haul flights is the age of the wx forecasts in your flight preparation papers vs. the quick and unexpected development of especially convective adverse weather.
If the wx is of such magnitude that passing through it is not possible, ATC will offer reroutings to pilots. But in most occasions, the decision rests on the aircrew, as they have to consider other operational aspects as time in their tanks, navigation equipment etc.
If the adverse weather consists of ISOL CB which can easily be circumvented, ATC will most likely not issue big reroutings and let the pilots do the wx avoidance on a tactical / ad hoc level.
If the aircrew is lucky to work at an operator with savvy dispatchers, they will pro-actively send an ACARS message to the crew, so they can prepare for the wx development ahead.
So most of the time, the flight crew has to come up with an idea. And their means of situational awareness are limited. As of now, the only means to really see what is ahead is the wx radar, usually having a range of 120-200NM. So it is common practice to ask aircraft ahead on track about the wx situation.
After gathering all the facts, the classic decision workflow starts. At my company, we use F-O-R-D-E-C, which stands for
Facts
Options
Risks
Decision
Execution
Control

...where "D" is the point at which you make your decision. Depending on the time available and the task to be solved, FORDEC may take 10 seconds (fire on board) up to half an hour or more (I guess https://en.wikipedia.org/wiki/Qantas_Flight_32 must have been such a case).
The "C" part (for "control" or "check") is a reminder to revisit your decision at a later point in time and check if it is still valid.
In the future, we will see more and more "connected" flight decks, where pilots can receive long-range wx information as live radar pictures directly into their electronic flight bag. This could have saved the lives of the people onboard AF447:

The yellow circle represents the range of the wx radar (what the pilots of AF447 could see) and the red polygons represent the known wx situation from a satellite picture.

In your situation, if you know there is we ahead that you can't yet see, who would you turn to first for more info, ATC or Dispatch? Also, what is the "control" part of FORDEC?


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How do SIGMETs arrive in a cockpit on a modern longhaul flight?
What is todays medium of choice (Voice Radio, ACARS,CPDLC,…) to receive SIGMET messages on a commercial longhaul flight, for example from continental Europe to the US westcoast?
Are there any differences in the regions that are passed (European Landmass, Oceanic, North American Landmass)?

Possible duplicate of What in-flight weather info is available to commercial pilots?

The linked question seems to be focused on information available within the US, so it doesn't seem to address the international aspect of this question.

This varies between airlines. In my company (large European Carrier) SIGMETs are uplinked to us via ACARS and then automatically printed on the cockpit printer.
The differences in regions is the format of the SIGMET. In the USA the points of a polygon are mostly described as list of DIR/DIST of VORs (eg 15NM NE STL). Very hard to read if you are unfamiliar with the area. Rest of the world uses coordinates (N3905W09046). Way better to locate on a chart.
There are efforts to automatically download (via satellite) and parse SIGMETs and display them in our electronic charting application in the aircraft EFB. This works currently so-so as there are surprisingly often typos or similar mistakes in a SIGMET text which kills the parser.


text:
Difference between Mach buffet and shock stall
What is the difference between Mach buffet and shock stall?

Transonic buffet is caused by the separated turbulent boundary layer striking the airframe (horizontal stabilizer, wings, fuselage) with considerable force causing a high amplitude vibration, which physically shakes the whole aircraft. It's highly destructive and all commercial aircrafts should avoid entering a buffet boundary zone. That's why commercial transonic aircrafts are limited, not only by IAS, but also with Mach number as well. The reason for separated boundary layer is a shockwave formation on the airfoil which causes a great adverse pressure gradient and separates the airflow from the wing. The transonic aerodynamic buffet is an imminent warning to the shock stall. As the shockwave strengthens and separation becomes even more severe there will be a great change in coefficients of lift, drag and pressure. These changes will induce more drag, and due to the Cp changes on the airfoil it will cause mach tuck to occur. Mach tuck is a phenomenon which causes a nose down tendency of an aircraft and it is very difficult to compensate it only with the elevators. When all that occurs then we are talking about a shock stall. Shock stall is associated with an aircraft dive while transonic buffet is a warning sign to the shock stall and physically shakes the whole aircraft with a quite destructive force.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
How do I know when to use flaps in glide approach or force landing?
During glide approach or practice force landing, I can see the aim point moving down. It means the aircraft will overshoot the field. But I am not sure when should flaps be used or which stage of flaps should be used. I concern that deploying flaps too early, the aircraft will not make it to the field.

This is not so much for normal power-on approaches, but the proper way to manage a forced landing approach is to use some way other than flaps to vary your sink rate as required.  Gliders do it with spoilers, which allows the glider's descent angle to be varied between maximum glide and nearly straight down at any time, which is why the one-shot landing aspect of gliders is really not such a big deal; it's easy to place it anywhere you want.
With power planes you use a forward slip as your variable drag tool.  As you are getting in close, a few hundred feet, you drop just takeoff flap to lower the stall speed and apply some forward slip, ideally roughly half of the maximum you can apply, to be about what seems to give you the correct descent path.
It's as if you had some power.  If you are overshooting, increase the slip angle to descend steeper like you were reducing power, if undershooting, decrease the slip to descend less steep like you were increasing power (a little bit).
Don't drop landing flap until you are down to the last hundred feet or so when making the field is assured.  Just about all aircraft can be slipped, but some may be restricted from slipping with full flap.
If you use and practice this method you will get good at placing the airplane precisely into a forced landing spot without power, and a forced approach will lose its terror as long as there is an open place to land.  I'd be disappointed with an instructor who wasn't teaching slipping to control descent rate in a power off emergency.

Yes.  It's rather like asking "How do you catch a ball?"  You can't really explain it - at least I couldn't - but you learn by practicing,

I don't advocate it but I actually use a more radical procedure for force landing scenarios.  My plane has manual flaps, worked by a center lever, which are quite powerful (won't work so well with electric ones).  I start out at half flap and if I need to adjust glide path, I hold the latch button down and work them up and down between 1/4 and 3/4 as if they were spoilers, coordinating pitch inputs to compensate for the changes caused by flap extension and retraction, and carrying a bit of extra speed margin.  It works quite well and I can place the airplane very precisely if I have to.

They should have a "trim wheel" for flaps instead of only 3 settings.  Landing by adding drag means you're high a bit, which means you'll make the field.  Safer for single (or no) engine.  But that's pretty much what a forward slip is.


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During a turn, will slip necessarily lead to altitude lost?
During aircraft turns, will slip necessarily lead to altitude lost?
During aircraft turns, will skid necessarily lead to altitude gain?

Slips and skids just mean that the nose is not pointed in the direction of the turn. Unless you do something else wrong, the airplane should remain level.

Why would skid ever lead to an altitude gain?

Think of a slip or skid that the aircraft is flying sideways (referred to as uncoordinated).  This does increase drag, and therefore it requires either more power, or given sufficient speed, increased pitch to maintain altitude compared to flying straight through the air in coordinated flight.
A "skid" is when the aircraft nose is pointed inside a turn where the pilot feels centrifugal force outside the turn, like in a skidding car.  In a slip, the nose is pointed outside the turn whereby the pilot feels a force of falling down into the turn.  In straight flight, whether the nose is pointed left or right, uncoordinated flight is called a slip either way: a forward slip for losing altitude, and a side slip for landing.


text:
What are stick position stability and stick force stability?

What are stick position stability and stick force stability?
What are the difference between them?
How will changing trim of an aircraft affect them?

Stick position stability.
In its broadest definition, stick position stability means: a larger aft stick deflection is required to maintain a lower constant airspeed. Or in an equation: $d\delta_e/dV > 0$, with $\delta_e$ being the elevator deflection, + = Trailing Edge Up
An aeroplane with stick position stability is easy and safe to control. If the pilot wishes to fly at a lower velocity, they only need to deflect the stick further aft in order to reach the larger Angle of Attack required to maintain lift. An aeroplane with stick position instability will react with an ever increasing nose-up deflection, requiring corrective opposite stick action.

Stick force stability.
An aircraft has stick force stability if deflecting the stick further away from trimmed position, requires a larger force: the stick feels as if it is loaded by a spring. Easy to achieve with irreversible flight controls, which are loaded by a mechanical spring. More difficult with reversible flight controls, where the airforces are directly fed back to the stick: at lower airspeeds the force gradient must be high enough to result in clear stick trim conditions (friction in the control loop plays a role here), at higher airspeeds the aircraft must still be controllable.
Stick position stability is a necessary condition for stick force stability, and stick force stability is an additional requirement for safe and easy control. And it is this stick force stability in a turn that required the implementation of MCAS in the B737MAX: stick force stability must be demonstrated in all flight states in order to obtain certification.

As far as certification is concerned, there are two kinds of stick force stability: speed stability as mentioned in your answer, and maneuvering stability (stick force/G). They stand apart.


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How does turning Errors in the Air Driven Artificial Horizon work?
Turning through 90°, 180°, 270° & 360°, the error is different. I can understand what is turning error and pitch error individually.

But why turning through different degree, the resulting error is different?

Rapidly becoming a nonfactor as electronic systems replace vacuum driven gyros:
https://www.flyingmag.com/g00/how-it-works-attitude-and-heading-reference-system?i10c.ua=1&i10c.encReferrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8%3d&i10c.dv=2
How It Works: Attitude and Heading Reference System
Attitude and heading reference systems (AHRS) have been providing heading and attitude information with greater accuracy and reliability than traditional mechanical gyros for years now. But how do these solid-state systems deliver this information, and how do they do so using increasingly smaller and lighter equipment?
Micro Electronics
An AHRS’s key features include micro-electronic mechanical gyros, accelerometers and a magnetometer or flux valve. The micro-electronic mechanical gyros are responsible for capturing motion data as an aircraft moves about all three axes. They do this by using vibrating components. As an aircraft changes direction, these vibrations deviate, and these deviations can be measured and used to calculate directional change data.
Gyro Drift
In order to account for gyro drift, which can produce erroneous data, an AHRS must also rely on accelerometers as well as a magnetometer or flux valve. The former uses gravity to serve as both an initial attitude reference as well as an inflight reference, whereas the latter uses Earth’s magnetic field to provide heading information.
The AHRS aggregates all the information from these different components and conducts complex algorithms and calculations to provide highly reliable attitude and heading data.
Side Note: Previously out of reach for private aircraft owners due to high costs, AHRS prices dropped remarkably as the result of the use and advancement of AHRS technology in the automotive industry. An AHRS today can be as small as a coin.

I just saw this one yesterday  http://www.wingbug.com/  Mounts on the wing and Wifis the flight attitude info to your iPad/iPhone. I would consider this as as a backup to my IFR Certified panel mounted system.  Would also be a great backup for vacuum system equipped planes.

This may be useful information, but it doesn't answer the question at all.

Yes, well too long for a comment, so to whomever downvoted it ....

Maybe you should post a new question and post this as an answer to that question? That's a good way to share information that isn't an answer to an existing question; I've done it a few times.


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Who must approve a globally distributed satellite to ground laser communication system?
Laser Light Communications (US) plan for several dozen optical high speed data links between satellites and ground is described in Aviation Week's article Big Gains On Horizon For Laser Communications Suppliers and Lightwave's online website: Laser Light to leverage free-space optics in space for Optical Satellite as a Service.

All Optical Hybrid Global Network (or HALO, as laser Light calls it)

The plan is to use lasers to establish optical links between satellites in Earth orbit (MEO) and between them and a network of ground stations.

According to the company's website, Laser Light will leverage 8 to 12 satellites in medium Earth orbit to create a network that will offer an initial service capacity of 7.2 Tbps. The satellites will pass signals among themselves and to the ground via free-space optics. The space interconnections will include 48 links of 200 Gbps apiece, as well as 72 steerable up/down links to Earth at 100 Gbps. (my emphasis)

edit: Confirming that the plan is to establish several dozen laser communications link between ground stations and satellites, from the article The Speed of Light: Laser Light and Optus Explain Optical Communications Partnership:

Laser Light’s hybrid network is broken into two elements: an OSS part and the Ground Network System (GNS). The OSS half is comprised of a constellation of eight to 12 Medium Earth Orbit (MEO) satellites, which beam down data to a GNS via a completely optical spectrum. The data then connects to terrestrial fiber infrastructure, such as the one Optus already has in place. (my emphasis)

above: Graphic from The Speed of Light: Laser Light and Optus Explain Optical Communications Partnership to Via Satellite Magazine Note: since the satellites are in medium Earth orbit (MEO) and not Geosynchronous orbit (GEO), these beams would not be fixed, but in fact scan repeatedly through tens of kilometers of airspace each.
These would not be narrow, millimeter-diameter beams like we see from laser pointers. In order to combat diffraction, they would actually be expanded to at least tens of centimeters in diameter or larger. There is also a chance they would be just outside the visible wavelength range in the (very near) infrared. So I would guess there is a good chance that - depending on the actual implementation - these beams might not actually pose any risk to a pilot if an aircraft passes though one, but I don't know that for a fact.
I would like to know who must approve globally distributed continuous laser data links between Earth stations and orbiting Satellites in the context of aviation safety.
The answers to the related question How does aviation deal with satellite and Moon laser ranging, and other scientific lasers in the sky? seem to suggest that there are some rules and best practices associated with ground-based lasers from observatories that are used intermittently, but in the case of bidirectional, near continuous laser traffic from dozens to perhaps hundreds of sites (each satellite has 72 independently steerable beams) the existing procedures (having two human spotters watching for planes) would not really be feasible.
There is some discussion here but I don't see any mention of aviation.

@mins Thanks. This is a bit different - maybe a 100 or more laser beams moving around day and night, 24/7 and probably not all in low air traffic locations where they can just shut off the internet if a spotter notices a plane in the area.

Yes of course. The problem here is that neither power or frequency is known. IR would be a problem for eyes for instance, but power may not be a problem at all, a minimum slant distance could be imposed, and 10 Gb/s may not need high powers (it's a matter of signal/noise ratio). On the ground radio-amateurs use IR leds (not lasers) for 10/30 km data links.

just because the beams are wider doesn't mean they're not problematic. The power required would be quite a bit higher than your laser pointer to get a decent signal at hundreds to thousands of kilometers of range, especially given the beam width being of necessity large. And to burn through atmospheric blooming your power requirements get to be even higher. Think of dozens or hundreds of ABM lasers being up 24/7. Would need to be a permanent no-fly zone of quite a size around each of them.

@jwenting yep I understand. I didn't wanted to raise a "sharks with lasers" alert. Visible sunlight is a few hundred watts per square meters. I'm asking here because I'd like to see if this has been addressed quantitatively somewhere, but I'm guessing these beams would also be of the same intensity. They have to be wide so that they won't diverge due to diffraction. For a given received signal strength, a beam starting with twice the diameter will go 2 times farther, but twice the power only gets you 1.4 times.

Oscar 25 on Kitsat-2 in 1993 started IR experiments for telemetry, and Oscar 40 in 2000 was also carrying an IR experiment payload. So I think this is definitely common in amateur-radio satellites, but a low data rates.

This is about lasers between satellites.  How is this even remotely related to aviation?  VTC

@abelenky thanks, but this is definitely about lasers between satellites and ground stations passing through aviation airspace. Thus the map showing eight satellites and dozens of ground stations and green lines connecting them, and the quote in bold: "The satellites will pass signals among themselves and to the ground via free-space optics"

@abelenky if you are the close-voter, please reconsider, based on my comment, a more careful reading of the question, and a second, confirming article (added in edit) that these are indeed lasers traversing airspace scheduled for 2018. Thanks!

At the end of it all, your question is basically: "Lasers could pass through aviation airspace.  Has anyone talked about this?"   That is not really a question about aviation.

@abelenky no that's not really correct, but perhaps I should refine the wording. The following is perhaps too much to ask in a single question, but ultimately I would like to find out if this system of laser beams between ground stations and space needs to be approved, and if so by whom (one international body or every country individually) and has that happened.

@abelenky I've made the question more specific.

How is this even tangentially related to aviation? Did this get migrated? Another "it has a bonus, you can't close it, no matter how off-topic it it & how many reviewers agree" episode.

@RalphJ lasers potentially passing through commercial aviation space are related to aviation and we might expect a substantial proliferation of ground-space laser communications links in the future. Your characterization of the bonus is incorrect. The question has been here for nearly four years now and has had 400+ views. The goal of this bonus is to simply encourage answers to be posted. Let's get to the bottom of this. If you're certain that future ground-space laser links are unrelated to aviation, consider posting that as an answer. Thanks!

@RalphJ an imperfect but helpful test for checking of a question is on-topic in this site is "Would the pilot want to know about it?" Examples of "no" might be questions about vegetarian in-flight meals or RGB LED "mood lighting" in the cabin. But I have to say that the regulations on lasers beamed from the ground and from orbit potentially through commercial airspace is something a pilot really might want to know about, do you disagree?

Well, I'm a pilot, and of all the things I'd want to know about, plenty of them are not "related to aviation" enough to be appropriate or this site. 400 views in 4 years is NOT a sign of great interest; 10,000 views in that timeframe would be more so.

@RalphJ My point is only that after 450 views and almost four years, the question has not been closed as off-topic. It's been vetted by the community. This argues against your premise that the question is only open because there's a bounty. Your comment, while catchy, misrepresents the situation and is therefore unhelpful.

(I've taken a wild stab at an answer, despite my not being a lawyer or legal expert of any kind, since nobody has written an answer in nearly four years.  If you don't like my answer, please feel free to write a better one.  I apologize in advance if I've abuse any legal terms.  It's quite possible that I have come to an erroneous conclusion.)
Your question seems to presume that there is some multinational body, or multinational rules, governing laser beams in the atmosphere.  However, there is no multinational agreement to regulate laser beams in the atmosphere.
Countries are sovereign, with no higher legal authority, and are not required to make any rules, laws, or enforcement bodies without voluntarily agreeing to do so.  Often countries realize that uniform standards or regulations are in their best interests, and make treaties or agreements with other countries to create laws and rules and enforce them.  Sometimes countries voluntarily abide by existing treaties or agreements without actually signing onto the agreement.  In the absence of such formal treaties or agreements between countries, individual countries are free to write, or to not write, whatever rules and laws they like.
One of the functions of the United Nations is to create a list of international treaties and agreements.  The list, known as the United Nations Treaty Series Cumulative Index, can be found here.  The most recent list as of this writing, current to 20 March 2013, sorted alphabetically, is here.  A quick search of the index for the term "laser" reveals only an "Exchange of notes constituting an agreement between the United States and Japan concerning a program for the cooperative research of Eyesafe Laser Radar."
In other words, there is no multinational agreement to create rules or laws regarding laser beams in the atmosphere, other than those that pertain to aviation safety.  Existing aviation safety legislation seems to agree that pointing powerful lasers at aircraft is something that should be regulated.  However, it seems likely to me that aviation safety treaties are silent regarding laser beams through the atmosphere that are not pointed at aircraft.
To sum up, it has been left to individual countries to write whatever laws they like regarding laser beams in the atmosphere not aimed at aircraft.  Currently it seems likely that few countries have written any such laws.  So companies can currently feel free to plan communications networks using laser beams between ground stations and satellites, since there are few or no laws to stop them, as long as they take care to not accidentally aim laser beams at aircraft.

In one sense this is very surprising, but I suppose airspace sovereignty is an overriding principle. Thank you for taking the time and addressing the question directly!


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What operational aspects of Alphabet's Wing drone delivery service will be the same as that of an airline?
The NPR News article and podcast FAA Certifies Google's Wing Drone Delivery Company To Operate As An Airline begins with:

The Federal Aviation Administration has certified Alphabet's Wing Aviation to operate as an airline, in a first for U.S. drone delivery companies. Wing, which began as a Google X project, has been testing its autonomous drones in southwest Virginia and elsewhere.
"Air Carrier Certification means that we can begin a commercial service delivering goods from local businesses to homes in the United States," Wing said in a statement posted to the Medium website.

The article, plus the BBC News's Google Wing drones approved for US home deliveries indicate that Wing (owned by Alphabet, which also owns Google) will be he first US drone delivery company to be run as an airline.:
See also Medium.com's Wing becomes first certified Air Carrier for drones in the US
Question: What operational aspects of Wing will be the same as that of other airlines? They won't sell seats of course, but will the file flight plans for example? Will they have licensed human pilots to oversee the drone's flight?

The Wing company, a Google spinoff, has won federal approval to operate its drone delivery system as an airline in the U.S.  Credit: Wing, Source

Customers who took part in Wing's drone delivery test program in Virginia approach their package after it was dropped on their lawn. Credit: Wing Source

@StephenS ah, I see now how "certified air-carrier" in one article became "airline" in others, thanks.

@StephenS I wonder if that's sufficient to post as an answer?

Converted to answer.

@StephenS now see, that didn't take long :-)

Under FAR Part 117, only certified "air carriers" are allowed to sell "aviation services" to the general public. Certification means that the FAA has determined the proposed operations, whatever they may be, will be reasonably safe.
FAR Part 121 covers most scheduled air carriers, which are commonly called "airlines". These are the only air carriers that the media knows about, so it's understandable that they'd conflate the two.
FAR Part 135 covers unscheduled and very small scheduled air carriers. I suspect this is where Google Wing would fall, but I haven't seen anything definitive so far.

Thanks for the concise yet seemingly complete answer! fyi I've just asked Why does Google's Wing drone have dimples?


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Can hours logged training to be a Sport Pilot apply toward the Private Pilot Certificate?
Can my training in a Sport aircraft with a Sport instructor be used to fulfill the requirements to become a Private Pilot?
As an example, assume I've started my training to be a Sport Pilot, but decided I'd rather be a Private Pilot.

Related question: What does a sport pilot have to do to get a private pilot certificate?

I've added the faa-regulations tag given that the only answer deals only with the faa.

Absolutely, you can log just about any flight time in an aircraft!
The definition of flight time is in 14 CFR 1.1 and says:

Flight time means:
(1) Pilot time that commences when an aircraft moves under its own
  power for the purpose of flight and ends when the aircraft comes to
  rest after landing; or
(2) For a glider without self-launch capability, pilot time that
  commences when the glider is towed for the purpose of flight and ends
  when the glider comes to rest after landing.

However, the instruction logged towards a sport pilot rating by a flight instructor certificate with a sport pilot rating (61.413) may not be used toward the requirements of the private pilot certificate.
If the instructor is a CFI certified under 61.181 then the instruction may also be used towards your private pilot certificate but you will need to be proficient to the higher standards, which may require additional training.
For those who already have their Sport Pilot Certificate, take a look at this question: What does a sport pilot have to do to get a private pilot certificate?

I think the second half of your answer is the actual answer :) you should emphasize that in the intro instead, since the question is asking "can training hours logged towards Sport Pilot work towards Private Pilot". If the applicant has earned a sport rating... then yes (additional rating experience + addl. rating checkride). Otherwise, no.

@egid The question has been updated to say that he has not earned a sport rating yet, which is how I originally interpreted the question.

It sounds like you're saying that if instruction is received from a CFI certified under 61.181, then you can count that instruction as time towards your PPL; whereas if the instructor merely has a "flight instructor certificate with a sport pilot rating", then that instruction time only counts towards your SPL, not your PPL. Is that right?

@TannerSwett That's correct.


text:
What are the specifications for the CFE738-1-1B?
I'm designing an aircraft for fun, and I've selected a CFE738-1-1B as the engine. It's never going to fly outside of X Plane, but it's still fun, so I'd like to make the X Plane version as realistic as possible. This means that I need to know a bit about this engine (it's used in the Falcon 2000, so any Falcon 2000 pilots, not including anything after the 2000 like 2000EX, you would be very helpful). What I need to know and haven't been able to find on the internet is the following:

Minimum N2 to avoid a hot start.
Length of time it takes from beginning of engine start to idle fuel flow.
Time from idle throttle to max throttle.
Time for N1 to spool up to max from idle.
Thrust curves.
SFC at half thrust at 0 and 40,000 feet.
Fuel flow at flight idle.

Any help much appreciated (Don't feel obligated to answer all of these in the same post)!

No guarantees as to accuracy but existing X-Plane models like this one would be helpful at least as a starting point.

May be helpful: Civil Turbojet/Turbofan Specifications. Also the Brazilian type certificate.

@fooot: Thanks, I'll check that one out.

@mins: Thanks, but those were two of the first things I used (the specifications sheet was actually my main resource for deciding on an engine)

http://competition.simu.free.fr/cockpit/Falcon_2000_PTM_V2r2_MCD%20Description%20des%20systemes.pdf - Chapter 7 is about the powerplant and contains lot of data. I'm currently at work so I've little time to check, but I hope this could help :)

That looks like it will be exceedingly helpful.


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What is it like to volunteer with Civil Air Patrol (CAP) as a pilot?
I saw various people talking about volunteering with CAP. I’m about to sit my test for my PPL, and am wondering whether there are opportunities to volunteer for search and rescue, or more generally, am interested to hear what is involved.
(I’m in the San Francisco Bay area, if anyone has specific local content as well.)

There are almost always opportunities to volunteer. However, joining CAP is a larger commitment than simply saying "I'd like to volunteer to fly." You will need to attend regular meetings and perform non-pilot duties such has becoming an administrative officer or participating in recruiting and fund raising activities. For some squadrons, the budgets are tight, and the ratio of pilots to flights can be high. The complaint I heard from CAP members back in Idaho was that they hardly ever got to fly. This may be less true in other areas.
My suggestion to you would be to contact your local squadron. In your case, this will be a squadron within the California Group 2 (San Francisco Bay). They have senior squadrons located in Palo Alto, Oakland, San Jose and elsewhere (senior squadrons are for adults 18+, whereas cadet squadrons are for children under 21. There are also composite squadrons for both seniors and cadets). Talk to them about their mission and what the experience would be like. If you're still interested, attend some meetings (you'll need to do this before they'll let you apply anyway). Then, after you have a good sense of what will be expected, if you believe in their mission, and you're willing to put in the time required, you should join.
If all you're looking for is a way to build cheap (or free) flight hours as a private pilot, then that is probably the wrong reason to join, and you will likely be disappointed.

*Note from editor: The oddity in the ages of membership for the senior and the cadet groups should be explained. A person may join as a cadet in a squadron up to their eighteenth birthday, however, if they became a cadet before that, they may continue as such until their twenty-first birthday. Anyone joining the Civil Air Patrol after eighteen enters into the senior branch.


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What is Tropopause height, and how is it determined?
I have seen the term "Tropopause height" used in a flight navigation plan. What is it and how is it determined?

It is not calculated. It is forecast.

Maybe it refers to the pressure altitude which is 30 thousand feet MSL. ?

@GürkanÇetin, no, it does not. See the answers, they are correct.

According to Wikipedia, the World Meteorological Organization defines tropopause as

The boundary between the troposphere and the stratosphere, where an abrupt change in lapse rate usually occurs. It is defined as the lowest level at which the lapse rate decreases to 2 ˚C/km or less, provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 ˚C/km. Occasionally, a second tropopause may be found if the lapse rate above the first tropopause exceeds 3 ˚C/km.

The tropopause height varies with latitude and season. The variation with latitude, based on annual mean conditions, is shown below:

Image from das.uwyo.edu
Troposphere can be identified only if the lapse rates (the rate at which atmospheric temperature decreases with increase in altitude) in the stratosphere and troposphere are known. Also, weather phenomena like thunderstorms shift the tropopause. As a result, the height of the tropopause is forecast based on localized weather conditions, and is not a fixed boundary.
The International Standard atmosphere, however, defines tropopause as lying between ~11,000 and 20,000 meters (geopotential altitude) above MSL.

It is not strictly true that thunderstorms shift the tropopause. They can, in severe cases, burst through it: But they do not move it.

The tropopause height varies with latitude and season.  Its height can be determined by looking at an atmospheric sounding as temperatures in the stratosphere increase with height.  This also means there is a strong static stability gradient at the tropopause.  The height can also be defined by a specific value of potential vorticity units (e.g. the 1.5 PVU surface).
Here is a current sounding from a balloon launched this morning at 12Z:

Here you can see a sharp transition in temperature lapse rate at about 200 mb between 11 and 12 km height.  Where the temperatue begins to rise with height (the kink around 200mb) is where the tropopause is located.

It might be interesting to add what is it useful for (I know it has something to do with optimal cruise level, but not details).

@JanHudec: This answer explains why the tropopause is an optimum altitude.


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What is Density Altitude?
I'm trying to get a deep understanding of the term: Density Altitude.
So I have read the explanations in my instruction book, and online articles.
One source explained it differently then the other which confused me.
Wikipedia defines Density Altitude as:

The density altitude is the altitude relative to standard atmospheric
conditions at which the air density would be equal to the indicated
air density at the place of observation. In other words, the density
altitude is the air density given as a height above mean sea level..".

https://en.wikipedia.org/wiki/Density_altitude
So if I would believe Wikipedia then I could look at the ISA table to find the altitude by using the pressure.
Here is an ISA table:

My instruction book (Aerodynamica, prestatieleer en vliegtuigtechniek by Bas Vrijhof on page 112, written in Dutch) claims this:

in de ISA is de dichtheidshoogte altijd gelijk aan de drukhoogte

Translated to English:

in the ISA the density altitude is equal to the pressure altitude.

So, let's say I'm flying in an aircraft, the pressure is "22.22 Hg", and the outside air temperature is -0.9°C. The altitude in the ISA would be 8000 ft. The Density Altitude would also be 8000 ft.
Skybrary defines Density Altitude as:

Density altitude is pressure altitude corrected for temperature.

Link: https://www.skybrary.aero/index.php/Density_Altitude
This explanation contradicts with the Wikipedia explanation:

the air density would be equal to the indicated air density at the
place of observation

On another wikipedia article I found this:

De relatie tussen temperatuur, hoogte en luchtdichtheid kan worden
uitgedrukt in density altitude.

Translated to English:

The relationship between temperature, altitude and air density can be represented as density altitude.

Link: https://nl.wikipedia.org/wiki/Opstijgen#Benodigde_snelheid
So in short, each source explains Density Altitude in their own manner, some contradict the other which confuse me.
So my question is:
What is Density Altitude?

https://en.wikipedia.org/wiki/Ideal_gas_law

Related question

I see that you've edited your question to remove the second part - there are any number of ways to verify your density altitude assumptions. I haven't tried this one but it might fit the bill.

@SteveV. While writing/updating the main question I suddenly understood the second question. So I rewrote the main question. After that, I took a look at your link and realized that Density Altitude is also affected by the dew point. So to say that The relationship between temperature, altitude and air density can be represented as density altitude is not enough, it is not wrong though. But the point is that the explanation I found and quoted here ignore the dew point. I'm just looking for a clear understanding. That's why I wrote the main question in the first place.

Density altitude is literally just the measurement of density. If you know the density $\rho$ you can convert that to density altitude and vice versa.

The concept of 'density altitude' is kind of like the concept of 'wind chill'.
Stick with me here, I'm going somewhere with this.
Cold weather is dangerous for the human body, and wind (because of increased heat loss on human skin) makes it worse. But how much worse? Is it worse to be outside in -10C temperatures with a 20 knot wind, or -15C temperatures with a 12 knot wind? The concept of 'wind chill' resolves those two values into a single easy number.
Density altitude works the same way. It's difficult and tedious to compare and contrast how an airplane will perform on a 25C day with a pressure of 29.80 at an elevation of 600 MSL, versus a 20C day with a pressure of 30.17 at an elevation of 1250 MSL. We need a way to mash all of these variables into one easy-to-use number. That number is density altitude.
So just as I can say "The wind chill is -10C" and it doesn't matter whether it's warm but windy or cold and calm, I can say "The density altitude is 2,000" and everyone will have the same idea of the expected performance of the airplane, no matter what combination of factors led to that result.
Once you start thinking of (and using!) density altitude as a simplification tool, its value becomes a lot more obvious.

Nice explanation. Perhaps it would be interesting to know how to compute the density altitude when ISA conditions are not met.

The AOPA article covers that.   Calculating Density Altitude
Density altitude in feet = pressure altitude in feet + (120 x (OAT - ISA temperature))
AltimeterPressure altitude is determined by setting the altimeter to 29.92 and reading the altitude indicated on the altimeter.
OAT stands for outside air temperature (in degrees Celsius).
ISA stands for standard temperature (in degrees Celsius).

Every resource on density altitude provides a way to compute it when ISA conditions are not met. Almost none explain why it's valuable. I wrote this answer hoping to focus only on why density altitude exists as a concept.

There is one significant difference though: while ‘wind chill’ is a ballpark figure for comparing things with fairly vague definition, density is the variable that appears in all of lift, drag and engine power equations, and well defined. You just don't have instrument to measure it directly, so you have to calculate it from pressure and temperature.

Density altitude is literally a measure of atmospheric density. There's a one-to-one correspondence between a density altitude and the atmospheric density $\rho$

@MikeY - You are 100% correct, but the original asker already knew that so I didn't mention it.

Try this article
https://www.aopa.org/training-and-safety/active-pilots/safety-and-technique/weather/density-altitude
As a pilot, we like higher Pressure and Cold Temperatures - it makes the air denser so the engine can create more horsepower. High Pressure systems, where the barometer reads above 29.92, and cold air, where the temperature is below 59F (I'm in the US) mean the aircraft will get off the ground sooner and climb better.  So - Winter! Ideal flying time from a performance perspective.
Summer, we may see the same increased barometer reading, but the higher temperature means the air is less dense (heat makes the air expand), so engine performance suffers. Even worse, if there is a Low Pressure system, combined with high temperatures, can make the airplane feel like it is taking off from a higher altitude.
So Density Altitude is the altitude that the airplane thinks it is - the barometer reading with temperature impact added to it.

I never considered this could be a problem. Thanks for explaining it!

It might be important that this relation only takes take off (and landing) into account. Once airborne and cruise a 'high' density altitude does improve performance by reducing drag. Flying is a huge pile of contradicting points and piloting is about navigating amidst them.

Suppose you are at a given place, with a given temperature, and the barometer shows –for example– 25.84 inches of air pressure. That's precisely the pressure at 4000 ft of altitude within the 'standard atmosphere'. Hence, you may say that the pressure altitude at that place where you are is exactly 4000 ft.
Suppose now that at the same given place the density of the air (measured or computed from pressure and temperature) is 1.121 Kg/m^3. That's precisely the density at 3000 ft of altitude within the 'standard atmosphere'. Hence, you may say that the density altitude at that same place is instead 3000ft.

Seems pretty straightforward!

Perfect explanation-- I think.  Introducing dew point doesn't alter the accuracy of this explanation, does it?  (Actually I'm afraid it does-- for a given pressure,  more humid air = less dense air, but no change in pressure.  Aaaarggghhh.)

Aren't you describing the pressure altitude?

@fab That doesn't matter, because the table of the standard atmosphere has a fixed correlation between pressure and density. In the example, the SA pressure at 4000 ft  is 25.84 inches of mercury, with a density 88,81% that at sea level (SA). No need to know the density figure, since what matters is that the density for that pressure (25.84 inches) is the SA density for 4000 ft...

I think you are confusing pressure altitude and density altitude. The table of standard atmosphere does have a fixed correlation between pressure and density because temperature doesn't change (at a given elevation). But in real atmosphere, the temperature will affect the density, even if the pressure doesn't change

Density Altitude, in a nutshell, tells you how the plane is going to perform, in particular the climb performance for takeoffs or go-arounds.
The performance tables in your POH are based on ISA, which for practical purposes no plane ever actually flies in.  That means you have to calculate the density altitude for the current conditions and look at that line in the tables to find out what the actual performance will be.
If the density altitude is very high (i.e. approaching your service ceiling), it's possible that your plane won't be able to clear obstacles/terrain or, in extreme cases, even get off the runway.  This happens frequently to non-turbo pistons in mountains in the summer, and it is occasionally bad enough that even airliners can't take off from airports like PHX and LAS.
Any time your planned flight will be High, Hot and Heavy (known as the three H's), you need to consider DA and check the performance tables to determine whether it will be safe.  High terrain may mean a different route via mountain passes; Heavy load may mean ditching passengers/cargo or fuel, and Hot may mean waiting until night or early morning.  If any of these aren't things you encounter regularly, e.g. because you live in a (relatively) cold and flat region, it would be wise to check with a CFI to refresh your knowledge and double-check your plans before you go.

Density Altitude is basically this:

Measure the density at a given location (or compute it)
Ask yourself: at what elevation do you find that density in the Standard Atmosphere?
The answer to question 2 is the density altitude.

More practically, here's how you can compute it:
$$\mathrm{DA_{feet}}=\mathrm{PA_{feet}}+ 120\cdot(T_{\mathrm{OAT}}-T_{\mathrm{ISA}})\tag{1}$$
where:

$\mathrm{DA_{feet}}$: Density altitude in feet
$\mathrm{PA_{feet}}$: Pressure altitude in feet
$T_{\mathrm{OAT}}$: Outside air temperature in Kelvin
$T_{\mathrm{ISA}}$: Temperature (in Kelvin) found in the standard atmosphere at $\mathrm{PA_{feet}}$ feet

If you wonder what the non-approximated equation for density altitude is, here it is:
$$\mathrm{DA}=\frac{T_0}{L}-\frac{T_{\mathrm{OAT}}}{L}\cdot\left(\frac{T_0-L\cdot\mathrm{PA}}{T_{\mathrm{OAT}}}\right)^{\frac{g}{g-R_s\cdot L}}=\frac{T_0}{L}-\frac{T_{\mathrm{OAT}}}{L}\cdot\left(\frac{T_{\mathrm{ISA}}}{T_{\mathrm{OAT}}}\right)^{\frac{g}{g-R_s\cdot L}}\tag{2}$$
where:

$\mathrm{DA}$: Density altitude in meters
$\mathrm{PA}$: Pressure altitude in meters
$T_{\mathrm{ISA}}$: Temperature (in Kelvin) found in the standard atmosphere at $\mathrm{PA}$ meters (i.e. $T_{\mathrm{ISA}}=T_0-L\cdot\mathrm{PA}$)
$L$: Temperature lapse $=0.0065 \mathrm{~K/m}$
$T_0$: Standard temperature $=288.15 \mathrm{~K}$
$g$: Gravitational acceleration $\approx 9.81 \mathrm{~m/s}^2$
$R_s$: specific gas constant for dry air $\approx 287.058 \mathrm{~J \cdot kg^{−1}K^{−1}}$

A few notes:

it can be derived directly from the barometric formula in the standard atmosphere and from the definition of density altitude
it assumes dry air and does not account for humidity
if $T_{\mathrm{OAT}}=T_{\mathrm{ISA}}=T_0-L\cdot\mathrm{PA}$, then it follows that $\mathrm{DA}=\mathrm{PA}$ (and one can really see that density altitude is basically pressure altitude corrected for temperature)

In order to derive equation 1 from equation 2, we need to compute the Taylor expansion (see this link) of equation 2 around the point $T_{\mathrm{OAT}}=T_0-L\cdot\mathrm{PA}=T_{\mathrm{ISA}}$ and only keep the constant and the linear terms:
$$\mathrm{DA}\approx DA(T_{\mathrm{ISA}})+\frac{DA'(T_{\mathrm{ISA}})}{1!}(T_{\mathrm{OAT}}-T_{\mathrm{ISA}})\tag{3}$$
If you run the math, you get:
$$\mathrm{DA}\approx\mathrm{PA}+(T_{\mathrm{OAT}}-T_{\mathrm{ISA}})\cdot\frac{R_s}{g-R_s\cdot L}\tag{4}$$
which finally looks similar to equation 1. The multiplicative term is:
$$\frac{R_s}{g-R_s\cdot L}= 36.13\mathrm{\frac{m}{K}}=118.55\mathrm{\frac{ft}{K}}$$
And that's the value usually approximated as 120

Try this: Density Altitude
Defined Types of Altitude Pilots sometimes confuse the term “density altitude” with other definitions of altitude. To review, here are some types of altitude:

Indicated Altitude is the altitude shown on the altimeter.
True Altitude is height above mean sea level (MSL).
Absolute Altitude is height above ground level (AGL).
Pressure Altitude is the indicated altitude when an altimeter is
set to 29.92 in Hg (1013 hPa in other parts of the world). It is
primarily used in aircraft performance calculations and in
high-altitude flight.
Density Altitude is formally defined as “pressure altitude corrected
for nonstandard temperature variations.”

The altimeter, although used primarily to give you altitude, is a pressure gauge. Through mathematical trickery in its innards, it will take the pressure and temperature and QNH and give you an altitude reading.
When you set 29.92 in the window, then the altimeter is truly measuring pressure, albeit in odd units of "pressure altitude". The reading has a one-to-one correspondence with other units of pressure. Just an odd nonlinear conversion to go from one to the other.
Pressure altitude is important, because airfoils fly by pressure. Thinner air but higher speed gives the same pressure, gives the same indicated airspeed. Planes in 1G flight stall at the same IAS, regardless of TAS.
When you make the temperature correction to the altimeter reading, you get density altitude. The altimeter is now measuring density not altitude or pressure. Density altitude is a measure of density. Again, just weird units with a nonlinear conversion to other measures of density.
Density altitude is important, because it tells you how many atoms of oxygen are in each parcel of air, and engines ingest oxygen to generate thrust. The same pressure but higher temperature and therefore less density, and you get less oxygen atoms per gulp.
So to summarize, Density Altitude is actually a measure of density, just an odd one.

"Airfoils fly by pressure",  actually they perform based on density altitude, which is pressure corrected for temperature (and to a lesser extent humidity).  Adjustments for "Standard conditions" gives us a reference point to say for example:  I'm at 5000 feet, it's 30 C, based on my pressure and temperature my plane will perform as if i'm at 8000 feet under standard conditions based on my POH charts.  Nothing "odd" about that.

It's important because higher TAS means a longer runway to get going, and "density altitude" tells one how close they are to the service ceiling for a given weight (to see if one can safely climb out).

In the equation $\frac{1}{2} \rho V^{2}$ there is a one-to-one mapping between the density term $\rho$ and the density altitude. That's my point. Density is also important because engine performance is critically tied to density (until we have battery powered aircraft).

@MikeY Airfoils fly by density, not pressure, as both lift and drag equations also use the $\frac12\rho v^2$ term (which is called dynamic pressure, but does not depend on static pressure but on density).

And don't forget props are airfoils too.  At lower density they must spin faster to generate the same amount of thrust (or change pitch if they can).  This is why aspirated fixed pitch really suffer at high density altitudes.

@JanHudec, as long as the dynamic pressures $ \rho_{1} V_{1}^{2} = \rho_{2} V_{2}^{2} $ it doesn't matter whether $ \rho_{1} = \rho_{2} $. Same pressure and same lift.

@MikeY $V$ is true airspeed. If densities are different ($\rho_1\ne\rho_2$), the true airspeed needs to be different, which matters quite a lot for take-off and landing roll. If indicated airspeed (which is really $\sqrt{\frac12\rho V^2}$) is the same, the lift is the same, but that's not what determines your take-off roll or your climb gradient. And either way the (static) pressure never comes into the equation at all, so saying airfoils fly by pressure is incorrect.

@JanHudec, lift is the integration of the pressure over the surface of a wing, taking the upward component. Since static pressure over a wing sums to zero, that is why it does not appear in a lift equation.

@MikeY, I know. You seem to know as well. So why do you still have that misleading statement in the answer?

Which exact statement do you think is wrong? Quote it.


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How can pilot remember when or where to do tasks such as changing radio frequency and change fuel tank?
As a student pilot, I sometime forget tasks such as changing radio frequency after reaching a location or switching fuel tank in long navigation.

These tasks happen in specific time or location and may not be in checklists

Is it something experience will help or
Are there method that can help pilot remember these tasks?

Make your own checklists
While the manufacturer provided check lists are a good starting point and generally cover the operation of the aircraft well the FAA does not forbid you from extending them. If you have a few more steps you feel are worthy of a checklist write up and print your own.
If you are switching tanks it sounds like you are flying a piper. Are you starting a time right before takeoff? If not you should be and you should always be changing tanks around the 30 minute mark. Another good rule of thumb with tank changes is to always execute them when near or overflying a field. Waiting an extra 5 minutes or switching 3 minutes early if their is a field below you is always a bit safer (should the engine cut out). Remember, for the pilot, a flight is not a journey from point A to point B it’s a series of maneuvers from one potential emergency landing spot to the next.
As a student pilot you are also still deloping habits which will be honed over time. You should debrief either with an instructor or do a self review after every flight. What went well what didn’t, what can be improved and how. The next time you get in the plane work these things and eventually you will build a good cockpit workflow.

I wonder about the reason for 'switching tanks'... I have owned three light airplanes since 2000, all three with wing tanks, and I always flew them with all the tanks permanently opened. In that way, the risk of mistakes when switching tanks is zero...

@xxavier the PA-28’s and other pipers don’t have a “both” selector so you can drain from only left or right there is no way to drain from both simultaneously. To keep the aircraft balanced and keep the tanks from running dry you alternate every half hour or so.

+1 for   'a flight is not a journey from point A to point B it’s a series of maneuvers from one potential emergency landing spot to the next'

As for changing radio frequency, that becomes 2nd nature after a while. If using ATC services (such as flight following, and I highly encourage that), you'll be prompted to change frequency from them to the local field after you let them you know you have the field in sight.  If not using ATC, you'll find you know to change when you don't hear anyone from the field you are landing making any broadcasts. And sometimes it is quiet, no one around, but you will still be broadcasting your position as you start lining up to enter the pattern.

For fuel, you can tack that on to various checklists so that every time you do anything, it becomes a habit to check whether you're on the fuller tank. For cross-country trips, the "anything" includes passing each checkpoint--which should be a lot less than 30 minutes apart. There are also apps and other devices that can be set to go off every 30 mins, but IMHO that's a crutch; if it fails, you may not notice and end up running one tank dry.
For radio, you should be on CTAF/Tower within 10nm or so, but if you don't have a GPS/app that tells you that, I'd add a checklist item to switch to 121.5 at Top of Climb (TOC) and to the destination CTAF at Top of Descent (TOD). That's if you're not using Flight Following, of course. Your CFI may not want you using FF because it might become a crutch or distract you from other things you need to focus on at this point, but do make sure you get some instruction and practice before your checkride.

Dave's suggestion to make your own checklists is a good one, especially for things that always happen at the same phase of flight. For example, something that you always do at Top of Climb could go on a personalized checklist. If you do make personalized checklists, just make sure to not omit something from the approved checklists!
That said, I don't know about you (and you don't say anything about where you're located), but one of the first few things I practiced doing even before setting out on my first cross-country navigation exercise with the instructor onboard, was to make a flight plan.
Now, I'm not talking about a full-fledged IFR flight plan complete with exact compass headings, specific wind correction, and so on. This was for daytime VFR flight, so much of that wasn't really needed.
What I did was to sit down at the kitchen table at home with an aviation map of the area and a flight plan form, decided on checkpoints, and figured out how to get from one checkpoint to the next, including determining the distance. For each leg, I'd note things like altitude restrictions (above 2000 ft AMSL here; specific clearance (from whom?) or below 3000 ft AMSL there; ...), a rough compass heading (I was navigating by landmarks, not instruments, but knowing whether to aim for 200° or 160° for a southerly leg was helpful), frequencies and call signs, and so on. Once done, I took a highlighter pen to a copy of the map and marked the planned route; I then carried that copy of the map, the flight plan, and airport directory sheets for both the intended airports as well as all other nearby airports, with me.
Once you have something like that, there is no real reason why you couldn't mark a checkpoint with some sign or text that tells you that you need to do something in particular. You could, for example, write "tank" in the margin to remind yourself that you should switch fuel tanks around that point, or "call XYZ 15nm" to remind yourself to call someone in particular and report your position as being about 15 nautical miles out.
While you should still be able to fly safely without any of this (so you do need some mental picture of, say, where the nearest airport is should your instructor suddenly tell you that "you just lost all your maps, and the radio's shot"), everything that you do on the ground before takeoff is usually one less thing you need to spend significant time and mental energy worrying about while in the air. Choose wisely which things to spend your energy on while you're actually flying.


text:
When to turn from crosswind to downwind to base in a circuit?
I was told by my instructor that my circuit spacing is inconsistent. I do not know how to look at the runway and use it to judge when to turn downwind and base. As a result, my base leg is sometime high and sometime low.
How do you determine when to turn at different leg in a circuit?

your turn from downwind to base will become more consistent if you keep speed, distance AGL, and distance from runway consistent.  Do not fly so far away you can't glide back if you lose power.  If you are consistent with step 1, it greatly helps all the way down to landing.  Dropping out of cruise is step 1.  I liked to go full idle, flaps 10, slow to 65 - 70, turn to base, trim to 65, and look.  Step 2 is dealing with high or low.  Where you drop out of cruise will depend on your plane, but also your power setting.  Higher rpm, lower rate of descent.

Like almost everything (aviation or otherwise), this is just something you learn with practice!
I was taught to turn downwind to base when the threshold was between 4 & 5 o'clock (in a RH circuit).
Here's a good graphical representation in a LH circuit.
]

At the end of your downwind leg, when you once again reach a 45° angle to the runway, do a medium 30° turn onto base.

(Image & Text source: http://www.ppl-flight-training.com/circuits-briefing.html)
As for the base leg being high or low - it shouldn't be a problem. You can easily correct this.
Too high:reduce power 50-100rpm, lower the nose slightly to maintain speed
Too low: Increase the power slightly.
As was commented, it is also worth considering the wind direction before you depart. On a perfect day, the wind will be directly down the runway towards you on final. Consider the effect of this on your circuit? I find it useful to draw the circuit, and an arrow with the wind direction. Then consider when to turn early/late as appropriate.
Finally remember the GOLDEN rule: You can ALWAYS go around. (Assuming you have a fan up front!)

@John, you may need to start the base to final turn sooner if the wind is blowing you towards the runway.   You don't want to be overturning to the left to correct for the wind blow you across final with that turn, that's how folks stall at low altitude.

How about turn from crosswind to downwind? How do you guys determine it?

@John where are you flying from out of interest. I find a  lot of UK airfields (certainly the ones Im most familiar with) have a published circuit. Its fairly common to have noise abatement procedures which would feed into these sort of decisions.

What it entails is developing the "sight picture" in your mind of what the runway looks like from the air when you are 45 degrees off the threshold at the nominal turn point.
It's my own personal opinion, but I think that for a brand new student the best method is to start off using a predetermined landmark on the ground to locate yourself precisely for the turn, and concentrate on internalizing the runway sight picture you see from that location.
As quickly as you can, you start to replace dependence on the landmark with judging the sight picture of the runway, until you can ignore the landmark but get reasonably close to it by runway eyeballing alone.
You must not develop a reliance on landmarks at your local airport as a crutch, because as soon as you go to another airport you're back to square one, but you need a starting point somehow.  You will need to be able to locate your turn reasonably well without depending on ground land marks before you can solo, so try to develop the correct sense as fast as possible.
One way to help with judging the 45 degree aspect of a runway with a well defined threshold edge is to study the apparent angles of the runway edge closest to you and an imaginary line extending along the threshold's edge, relative to the horizon. They should form a "level" V as shown below.

At least you've eliminated fast or slow, which (because energy is proportional to the square of your speed) makes it much more complicated.  Trimming to approach speed after turning to base makes it a question of high (reduce power/add flap) or low (add power).
Because of wind, landing patterns will never be perfect, but improvements can be made to make them more consistent.  It is the distance from the runway on your downwind that needs to be worked on first.  Landmarks and old saws such as "half way up the spar" help train your eye, as well as your speed and AGL.
Landing can be done in stages (example Cessna 172):

Enter downwind at consistent speed (around 100 knots), AGL, and distance from runway.
At a chosen point along the runway reduce power and drop to approach speed.
 Add flaps 10.  Work on establishing your best spot to do this.
Turn to base and trim to 65 knots, look high or low?
Use power and/or flaps to adjust rate of descent to set up your final.

If you do this consistently, it should make your approaches much easier.  "Good patterns make good landings".

I liked the advice to enter downwind "AGL". You wouldnt want to enter it below ground level :)


text:
Can the phrases "carbon fibre reinforced polymer composites" (CFRP) and "carbon fibre-epoxy composites" be used interchangeably?
Does the "polymer" in CFRP imply the use of an epoxy resin?

Welcome to aviation.SE! If you don't get a good response here you could also try engineering.SE; there doesn't seem to be anything in your question that's specific to aviation.

I believe that polymers other than epoxy resin are used but don't have time to check properly. So I'd say epoxy is a polymer but not all polymers are epoxy. I admit I'm not 100% on it though. Asking on Engineering is a good shout.

No.
Epoxy resin is more specific than the terms polymer or plastic from CFRP. CFRP does also include carbon fibre composites with other duroplastic matrix materials (e.g. phenolic resin) or even thermoplastic matrices.